Qingping Wang

Removal of Pb(II) from aqueous solution using modified and unmodified kaolinite clay.

Modified kaolinite clay with 25% (w/w) aluminium sulphate and unmodified kaolin were investigated as adsorbents to remove Pb(II) from aqueous solution. The results show that amount of Pb(II) adsorbed onto modified kaolin (20mg/g) was more than 4.5-fold than that adsorbed onto unmodified kaolin (4.2mg/g) under the optimized condition. In addition, the linear Langmuir and Freundlich models were used to describe equilibrium isotherm. It is observed that the data from both adsorbents fitted well to the Langmuir isotherm. The kinetic adsorption of modified and unmodified kaolinite clay fitted well to the pseudo-second-order model. Furthermore, both modified and unmodified kaolinite clay were characterized by X-ray diffraction, Fourier transform infrared (FT-IR) and scanning electron microscope (SEM). Finally, both modified and unmodified kaolinite clay were used to remove metal ions from real wastewater, and results show that higher amount of Pb(II) (the concentration reduced from 178 to 27.5mg/L) and other metal ions were removed by modified kaolinite clay compared with using unmodified adsorbent (the concentration reduced from 178 to 168 mg/L).

Heterogeneous Fenton-like oxidation of monochlorobenzene using green synthesis of iron nanoparticles

Iron nanoparticles (Fe NPs) were synthesized using tea extracts as a catalyst for the Fenton-like oxidation of monochlorobenzene (MCB), where 69%, 53%, and 39% of MCB were, respectively, degraded by Fe NPs synthesized using green tea extracts, oolong tea extracts, and black tea extracts. Fe NPs synthesized using green tea extracts (GT-Fe NPs) demonstrated the best degradation since green tea contains a high concentration of caffeine/polyphenols used as both reducing and capping agents in the synthesis of Fe NPs. This was confirmed by SEM image, EDS, and XRD pattern of GT-Fe NPs. In addition, batch experiments show that the oxidation of MCB and the removal of chemical oxygen demand (COD) using GT-Fe NPs were 81% and 31%, respectively, at optimal conditions, where dosages were 0.6g/L GT-Fe NPs, 0.045 mol/L H2O2, and initial pH of 3.0. Compared to homogeneous Fenton oxidation of MCB, GT-Fe NPs as a heterogeneous catalyst indicate that Fe(2+) and Fe(3+) leached from GT-Fe NPs nanoparticles and consequently reduced the formation of iron sludge. Finally, GT-Fe NPs were successful in removing MCB from wastewaters, and the possible Fenton-like oxidative mechanism of MCB was proposed. The proposition was based on adsorption of MCB on the surface of GT-Fe NPs, decomposition of H2O2, generation of hydroxyl radicals, and oxidation of MCB.

A label-free ultrasensitive electrochemical aptameric recognition system for protein assay based on hyperbranched rolling circle amplification

A label-free ultrasensitive electrochemical aptameric sensor which combined the advantages of an aptamer and hyperbranched rolling circle amplification (HRCA) has been developed for specific recognition of a platelet-derived growth factor B-chain (PDGF-BB).

Simultaneous determination of phosphate and calcium in river water samples by capillary zone electrophoresis with UV detection

Capillary zone electrophoresis (CZE) with UV detection at 214 nm was developed for the simultaneous determination of phosphate and calcium in waters, where Ca2+ reacted with 2,6-pyridinedicarboxylic acid (2,6-PDCA) in the electrolyte to form anionic . Consequently, and were simultaneously separated by CZE using an electrolyte containing 10 mM 2,6-PDCA and 0.75 mM tetradecyltrimethylammonium bromide (TTAB) at pH 7.0. The results showed that reasonable resolution with low interference from other ions in the water was achieved. Linear calibration curves were obtained in the concentration range of 0.01–0.5 mM with hydrodynamic injection. The detection limits (S/N = 3) were 5 µM for and 2 µM for . The separation of and occurred within 6 min with small relative standard deviation of peak areas (<5%). The method was successfully applied to the determination of and Ca2+ in river water samples, and provided a fast and simple procedure that required no modification of the CE instrument.

A colorimetric sensor for pH utilizing a quinoline derivative

A simple sensor utilizing a simple aminoquinoline derivative (5-(quinolin-8-yliminol) pentanal, QYP) has been successfully developed for the naked-eye colorimetric assay of pH. The QYP compound presents strong solvatochromism due to the solute–solvent interaction, and it is sensitive to a pH change in the solution. The color of the solution changes from orange to colorless upon increasing the pH value, which is well consistent with the corresponding UV/vis absorbance variation. UV absorbance has a direct linear relationship with the pH values in the range of 4.0 to 8.0 in phosphate-buffered saline, and the corresponding color variation could be distinguished readily by the naked eye.

A Portable Immunosensor with Differential Pressure Gauges Readout for Alpha Fetoprotein Detection

A portable, affordable and simple detector is requested in a “Point-of-Care-Testing” (POCT) system. In this study, we exploited the potentialities of Differential Pressure Gauge (DPG) to the orientation of POCT technology. Alpha fetoprotein (AFP) was chosen as a model analyte that could specifically recognized by its antigen, and a tiny outfits equipped with a DPG was employed as the signal readout. Pt/SiO2 nanospheres were synthesized and modified with the detection antibody. In the presence of target, a sandwich of immunocomplex specifically formed and the Pt/SiO2 had been modified on the capture antibody. Which then can be dissolved to release plenty of Pt and the suspensions were transferred into a closed vial filled with appropriated amount of hydrogen peroxide. Subsequently, hydrogen peroxide was decomposed to produce oxygen, resulting in the enhancement of pressure in the closed vial and which can be detected by DPG easily. Under the optimized conditions, the read out signal from DPG had a direct relationship with AFP concentrations in the range of 10~200 ng/mL, and the detection limit was as low as 3.4 ng/mL. The proposed portable sensor had been successfully applied to detect AFP in serum samples with satisfactory results. This strategy holds a great promising in biological analysis as its convenient operations, reliable results and flexible apparatus.

A micro-pressure sensor-based analytic platform and its application in thrombin quantification

Although great efforts have been devoted to the design of various kinds of biosensors in recent years, a universal sensor fabricated for daily usage with convenient operation is rare. In this study, based on the fact that hydrogen peroxide can be decomposed by catalase to produce oxygen, which can reinforce the pressure in a closed container, a commercially available micro-pressure sensor (MPS) with great sensitivity was employed to fabricate an analytic platform for detecting biomedical targets. Taking thrombin as the example, it induces the formation of a catalase-labelled complex, which can be separated and subsequently added to a closed container equipped with a MPS as the pressure monitor and data recorder. Experimental data show that the variation in the pressure recorded by the MPS has a close relationship with the amount of thrombin. The results indicate that biomedical targets can be quantitatively detected using this method without complicated operation, similar to personal glucose meters. Such an original model has great promise in the field of clinical assays once combined with biosensor technology.

The toxicity of graphene and its impacting on bioleaching of metal ions from sewages sludge by Acidithiobacillus sp.

The increasing production of graphene raised concerns about their releasing into sewage sludge, however, there is little information about graphene impacting on the growth of bacteria and hence their bioleaching of metal ions from sewages sludge. In this study, we reported that Acidithiobacillus sp., isolated from sewages, were used to bioleach Cu2+ and Zn2+ from sewages sludge in the presence of graphene. The negative effect on the growth of Acidithiobacillus sp. and dose-dependent were observed in presence of graphene, where the optical density (OD420) of the culture decreased from 0.163 to 0.045, while the bioleaching efficiency of Cu2+ (70%-16%) and Zn2+ (80%-48%) were also reduced when the graphene dose decreased from 50 mg L-1 to 1 mg L-1. Furthermore, scanning electron microscopy (SEM) and atomic force microscopy (AFM) confirmed that the direct contacts between graphene and cell at 1 mg L-1 graphene caused cell membrane disruption, while Acidithiobacillus sp. grew better by forming dense biofilms around the suspended graphene at a 50 mg L-1. LIVE/DEAD staining further demonstrated that almost no live cells were detected at 1 mg L-1 graphene. The toxicity of graphene could generally be explained by depending on the concentration of graphene. The new findings provide an insight into dose dependence, which impacted on the growth of Acidithiobacillus sp. and their bioleaching of metal ion from sludge.

Bioleaching of heavy metals from sewage sludge using Acidithiobacillus thiooxidans

Acidithiobacillus thiooxidans was isolated from sewage sludge using the incubation in the Waksman liquor medium and the inoculation in Waksman solid plate. It was found that the optimum conditions of the bioleaching included solid concentration 2%, sulfur concentration 5 g⋅L−1 and cell concentration 10%. The removal efficiency of Cr, Cu, Pb and Zh in sewage sludge, which was obtained from waste treatment plant, Jinshan, Fuzhou, was 43.65%, 96.24%, 41.61% and 96.50% in the period of 4∼10 days under the optimum conditions, respectively. After processing using the proposed techniques, the heavy metals in sewage sludge did meet the requirement the standards of nation.